George b



UNITED STATES PATENT OFFICE.

B. BUBNHAM, OF BQBOSOLVAY, CALIFORNIA.

PROCESS OF OBTAINING POTASSIUM SODIUM SULFATE SALIR'E LIQUOBB.

No Drawing.

To all whom it may concern:

Be it known that I, Gnonos B. BURNHAM, a citizen of the United States, residing at Borosolva in the county of San Bernardine and tate of California, have invented a certain new and useful Process of Obtaining Potasium Sodium Sulfate from Saline Liquors, of which the following is, a specification.

This invention relates to the process of obtainin potassium sodium sulfate from saline liquors containing otassium by means of adding sodium sul ate, or a solution of sodium sulfate.

An object of the invention is to provide a cheap recess for obtaining potassium sodium su fate from saline liquors and also to obtain the potassium sodium sulfate free from carbonates and borates where large quantities of the latter are plesent in the 11 nor.

he invention possesses .other advantageous features, some'of which, with the foregoing, will be set forth in the following description where I shall outline in full one form of the process of my invention. I shall describe the process as applied to mother liquorbrines left over in the process of recovering potash from Searles Lake in California, but it is to be understood that the recess is not limited to this particular rine.

These mother liquor brines are relatively high in sodium. potassium, chlorid, carbon- 95 ate and hernia, and low in sulfate.

40 double salt of potassium is in sulfate than in potassium. or

treatment of these brines to obchlorid produces a deposit process of prosulfate a pure obtained free Hitherto, tain potassium of mixed salts, but with my ducing potassium sodium ions in the brine may vary greatly and still be able to produce potassium sodiuih sulfate. The theorcticnl limit of the amount of the sulfate ions in the brine must be such that the concentrated brine is not saturated 56 with sodium sulfate. However. cven if the concentrated brine is nearly but not quite Specification of Letters Patent.

Application fled June 18, 1828.

Patented Nov. 11, 1919.

Serial No. 304,499.

saturated with sodium sulfate it can still be used to produce the double salt. A small amount of sodium sulfate is added and a small amount of potassium sodium sulfate [5 obtained. The yield is small because of working with the brine too close to the saturation point of sodium sulfate, and small yields are not desirable commercially. The farther the brine is away from this saturation oint of sodium sulfate the more sodium sul ate can be added to the brine and the greater will be the yield of the double salt. For this reason, it is commercially more feasible to use brincs much richer in tassium than in sulfate, for then the brine -would be far from the satumtion point of sodium sulfate.

In the solution 0 sodium sulfate in water is added to the mother liquor brine of Searles Lake, which is fairly rich in potassium, and is therefore far from the saturation point of sodium sulfate. Care is taken not to add too muchsodium sulfate solution to cause the resulting liquor to become immediately saturated with sodium sulfate upon eva oration. The amount of sodium sulfate that should be added to obtain the best results will" depend upon the composition of the .brine.

This mixture of mother liquor brine and sodium sulfate solution is then allowed to evaporate and the double salt, potassium soduun sulfate, (K,Na) S0,, is crystallized out. Evaporation is continued until another salt begins to crystallize out. At this point the remaining liquor isremoved, and the potassium sodium sulfate is gathered,

dried or filtered, and is then ready for the market as a fertilizer. 7

Sometimes evaporation may continue a little beyond the point where other salts begin to crystallize. if these other salts crystallize out in such small proport on that they do not materially impair the "aluc of the potassium sodium sulfate being deposited.

In some cascs it may be dcsirahlc to add solid sodium sulfatc dircctly to thc mother liquor briuc iustcad of adding a solution of sodium sulfate in water and evaporating. in such cases a chemical reaction takrs place whcrcby the sodium sulfate gocs into solution and polus ium sodium sulfate crystal-- lizcs out of thc l1lllilnll at thc sanw limc. The evaporation lll) is thus Plllllllhlllll by preferred form of my process a .tlus method, but it usually requires the adnot saturated with sodium sulfate, but containing suflicient potassium ions to more than saturate the liquor with potassium sodium sulfate upon the addition of sodium sulfate, which consists in adding sodium sulfate whereby potassium sodium sulfate is crystallized out.

2. The recess of obtaining potassium sodium suliate from liquors containing potassium ions and not saturated with sodium sulfate, which consists in adding a solution of sodium sulfate and evaporating the liquor to crystallize out potassium sodium sulfate.

3. The process of obtaining potassium sodium sulfate from liquors containing potassium, and other ions, which consists in adding a solution of sodium sulfate, evaporating the liquor to crystallize out potassium sodium sulfate, continuing the evaporation to saturation with other salts, removing the liquor from the deposited crystals, and recovering the potassium sodium sulfate.

GEORGE B. BURNHAM. 

